Question 328580
The quadratic formula for finding roots is
 {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
You need to know what a, b, and c refer to
This formula assumes that the equation is in the form
{{{ax^2 + bx + c = 0}}}
Your equation is already in this form:
{{{2x^2-5x-2 =0}}}
{{{a = 2}}}
{{{b = -5}}}
{{{c = -2}}}
plugging in the numbers:
 {{{x = (-(-5) +- sqrt( (-5)^2-4*2*(-2) ))/(2*2) }}}
 {{{x = (5 +- sqrt( 25 + 16 ))/4 }}}
{{{x = (5 +- sqrt(41))/4}}}
I'm guessing that {{{c}}} should be {{{2}}} and not {{{-2}}}. That would make the
solution
{{{x = (5 +- sqrt(25 - 16))/4}}}
{{{x = (5 +- sqrt(9))/4}}}
{{{x = (5 + 3)/4}}}
{{{x = 2}}}
and
{{{x = (5 - 3)/4}}}
{{{x = 1/2}}}
These are the 2 roots.
If {{{c = -2}}} for real, then stick with {{{x = (5 +- sqrt(41))/4}}}